The invention concerns a method of processing the connecting surfaces between a marine engine frame and the associated bearing support, which parts wholly or partially surround a crankshaft, said bearing support being removed to expose the connecting surface of the engine frame and facing towards the bearing support, and also an apparatus/setting-up system for the execution of the method.
During the use of marine engines, a pitting by erosion occurs on the connecting surfaces between the engine frame and the bearing support. The result of this pitting, which occurs in the connecting surface, is that the two parts do not fit together in an optimum manner, so that there is a risk that crankshaft and bearings, which the two parts surround, describe asymmetrical rotations, whereby there is a risk of bearing seizure. In order for a crankshaft to function in an optimum manner, it is thus important that the connecting surfaces between the engine frame and the bearing support are uniform and without play. Therefore, it is important to carry out a processing of these connecting surfaces as soon as this pitting is detected
The known technique involves the removal of the bearing support itself and thereafter the removal of the entire engine frame in order that the two opposing connecting surfaces can be processed, preferably by a mechanical method. In that the engine frame weighs up to several hundred tons, such a procedure involves great costs and a great consumption of time. It is desirable, therefore, to be able to develop a method for the processing of these connecting surfaces without the necessity of having to remove the engine frame, and thus effect a processing of at least this free connecting surface, while the bearing support itself can be processed in a normal manner.
This is made possible with a method of the kind disclosed in the preamble, and where there is also established an auxiliary plane which is setup/extended following the centreline of the crankshaft, and a second auxiliary line at right-angles to this line, and that an in situ processing of the connecting surface of the engine frame is effected at an angle which is a function of the position of the auxiliary plane.
It is expedient that the actual establishing of the auxiliary lines can take place as disclosed in DK 167,080.
It is thus important that there is established an auxiliary plane which determines those surfaces which must be processed in a uniform manner in retaliation to the crankshaft, so that no oblique grinding of the surfaces takes place. When this auxiliary plane is registered and coded in, it is subsequently possible to carry out a processing of those surfaces in which pitting has occurred. This processing of the surfaces is preferably effected by means of a spark machining, where in a manner of speaking the spark electrodes work in reverse, in that the electrodes are moved from below and up towards the connecting surface at a given frequency. The liquid which must be used in order for the spark machining to take place is supplied through a hole drilled in the engine frame itself. This hole also serves the mounting of an assembly bolt for the assembly of the engine frame against the bearing support, but can now expediently be used for the feeding through of the liquid. It is important that the liquid flow is such that it seeks to remove the xe2x80x9cswarfxe2x80x9d which arises during the spark machining, so that the electrode processing can result in an even and smooth surface, and so that sparks are not emitted in the areas where this must not take place.
It is expedient to effect the actual setting-up by means of lasers, in that the laser is set up in accordance with the centerline of the crankshaft, and that subsequent use is made of angle lasers for lateral setting up, in that this angle laser has the centerline of its light parallel with a bore in the engine frame, said bore being substantially at right-angles to the crankshaft. This plane is transferred to the electrodes by means of a reference sensor from the auxiliary plane. The reference sensor is an electronic, two-coordinate gyro with an accuracy of 0.002xc2x0. In this way it is ensured that the auxiliary plane, which is necessary for the spark machining to take place at the corrected angle, is positioned correctly.
It is also expedient for the spark machines to be two in number, i.e. one on each side of the crankshaft, and that the spark electrodes are encapsulated in a vessel, in the sense that the actual upper surface of the electrode is naturally not encapsulated, but where the liquid covers this. It is hereby ensured that a flushing away of elements from these surfaces is effected, and where the actual supply of liquid takes place.
The invention also concerns an apparatus/setting-up system for the execution of the method, and where this comprises a base plate on which at least two spark electrode machines are placed, said spark electrode machines being mounted on a vertically-displaceable column, and that the apparatus/setting-up system also comprises means for the positioning of the base plate seating.
Also disclosed is an expedient encapsulation of the spark electrodes in such a manner that it is ensured that there is liquid present during the processing.
Finally, the invention also concerns the use of the method and the apparatus.